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BIG PHYSICS, BIG QUESTIONS –

Hunter-gatherers got on fine with Europe’s first farmers

By Michael Marshall

Farmers would have tended to eat domestic animals, while hunter-gatherers enjoyed more freshwater fish

(Image: Burke/Triolo Productions/Getty Images)

Europe’s first farmers lived alongside a ghost people. Even some 2000 years after farming began to spread through the continent, some people were still clinging to the hunter-gatherer lifestyles that had been practiced formerly. The first farmers and last of Europe’s hunter-gatherers lived alongside each other for millennia and even shared burial sites.

“After 2000 years of agriculture in Europe, we still find hunter-gatherers,” says Ruth Bollongino of Johannes Gutenberg University in Mainz, Germany. “We never expected anything like this.”

Farming was invented in the Middle East about 10,500 years ago, and spread rapidly. It reached Europe about 7500 years ago, and continued to expand westwards – apparently because the incoming migrating farmers thrived and outcompeted the native hunter-gatherers. From this time forward, there are no archaeological records of hunter-gatherers in Europe, suggesting that the lifestyle had effectively died out. “We had no archaeological hints of their existence,” says Bollongino.

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But the genetic evidence tells a different story. Analysis of modern and ancient DNA shows that modern Europeans carry genetic elements from those early farmers – but many also carry DNA from early hunter-gatherers, says Bollongino. Apparently, Europe’s original hunter-gatherers did not simply disappear, but instead mixed, and seemingly interbred, with the incoming farmers.

Side by side

Attempting to figure out when this admixture happened, Bollongino and colleagues obtained DNA from the bones and teeth of 29 bodies found in Blätterhöhle cave in Germany. The cave seems to have been a burial site.

The team sequenced mitochondrial DNA from 25 of the bodies, and used carbon dating to work out how old they were. The oldest samples are 10,300 to 11,200 years old – and so date from before European farming. Unsurprisingly, the genetic signatures were typical of hunter-gatherers. Some of the bodies were much more recent, dating from between about 6000 and 5000 years ago, and at first glance, they appeared to carry genetic signatures typical of Europe’s incoming farmers.

But then the team examined the samples’ isotope content, revealing these ancient people’s diets. This analysis revealed that, as expected, the ancient hunter-gatherers mostly ate wild animals. But the more recent group, initially thought to be exclusively farmers, actually divided into two populations with different diets.

One of these populations clearly practiced farming, and ate mostly domestic animals. But the other population, living alongside them, mostly ate freshwater fish. This is a typical hunter-gatherer diet and indicates that the lifestyle persisted in the area until 5000 to 6000 years ago, perhaps 2000 years after farmers entered the region.

Not just farmers

The migrant farmers, and the local hunter-gatherers, must have lived as neighbours for many years. “They shared the [Blätterhöhle] burial place for 400 to 800 years,” says Bollongino. “We are pretty sure they were in contact.”

The two cultures may even have traded with each other, or exchanged information. “We know from examples from Africa and Indonesia that they can live side by side for centuries,” say Bollongino. “They profit from each other.” They may also have interbred&colon; Bollongino’s team found three chunks of DNA, normally found in hunter-gatherers, in the farmers’ genes.

Clearly, farming did not outcompete the hunter-gatherer lifestyle immediately. “Hunter-gatherers don’t need to work that hard,” says Bollongino. “Being a farmer is a full-time job.” But in the long run, farming populations grow much bigger than those of hunter-gatherers due to the sheer quantities of food produced.

It is not clear why the hunter-gatherers have left little trace in the archaeological record. It may be that the record itself is poor. “We don’t find many farming settlements either,” says Bollongino. There is some evidence that European populations repeatedly crashed between 7500 and 5000 years ago. “Maybe we do not find a lot because there were not many people.”

Multiple moves

The migration of early farmers was far from the only major population movement that shaped Europe’s genetic diversity, says Guido Brandt, also at Johannes Gutenberg University, who was not involved in Bollongino’s study.

Brandt and his colleagues have chronicled how the genetic makeup of Europeans changed between 5500 and 1550 years ago, using genetic samples from the Mittelelbe-Saale region of Germany. This was after the first influx of farmers, but Brandt’s team could identify three important shifts in the population during this time period.

Soon after the rise of farming, a group of hunter-gatherers moved south into Germany from Scandinavia. This migration may have given rise to the hunter-gatherer culture that Bollongino found. Soon afterwards, there were two successive waves of migration of farmers and pastoralists into central Europe, first from the east and then from the south-west. Together, they show that by 4500 years ago, the genetic diversity of modern Europe was largely in place.